MONOPHASIC STATE OF INSULIN SECRETION IN ISOLATED RAT ISLETS OF LANGERHANS BY K+, Ca2+ AND GLUCOSE

Isolation of rat islets of Langerhans was carried out by using collagenase and the destruction of exocrine tissue was performed through the injection of Hanks' solution into the common bile duct. The identification of the islets was done by techniques including the use of a stereomicroscope against a black background. Vital staining was done by an injection of neutral red solution through the abdominal aorta to observe the red tinted islets. Immunofluorescent staining with anti-insulin was done to identify islets and nuclear staining was done with propidium iodide. The microorgans were detected by a confocal microscope equipped with a laser source. The secretory activities of the islets was investigated by in vitro measurement of insulin and the effects of various concentrations of glucose, potassium and calcium ions were studied. It was found that the insulin secretion by these agents obeyed a monophasic trend which points to the depolarization effect on cytoplasmic membrane induced by these agents.